Rum for bad one outside saloon, perhaps (7)
I believe the answer is:
bacardi
'rum' is the definition.
(I've seen this before)
'bad one outside saloon perhaps' is the wordplay.
'one' becomes 'I' (Roman numeral).
'outside' indicates putting letters inside.
'saloon perhaps' becomes 'car' (I've seen this before).
'bad'+'i'='badi'
'badi' enclosing 'car' is 'BACARDI'.
'for' acts as a link.
(Other definitions for bacardi that I've seen before include "white spirit" , "White rum, first produced in Cuba" , "Drink" .)